From 27c7acf22047fbe4ec4cc36b7c2610dba227697c Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Wed, 5 May 2010 23:57:37 +0200 Subject: USB: serial: reimplement generic fifo-based writes Reimplement fifo-based writes in the generic driver using a multiple pre-allocated urb scheme. In contrast to multi-urb writes, no allocations (of urbs or buffers) are made during run-time and there is less pressure on the host stack queues as currently only two urbs are used (implementation is generic and can handle more than two urbs as well, though). Initial tests using ftdi_sio show that the implementation achieves the same (maximum) throughput at high baudrates as multi-urb writes. The CPU usage is much lower than for multi-urb writes for small write requests and only slightly higher for large (e.g. 2k) requests (due to extra copy via fifo?). Also outperforms multi-urb writes for small write requests on an embedded arm-9 system, where multi-urb writes are CPU-bound at high baudrates (perf reveals that a lot of time is spent in the host stack enqueue function -- could perhaps be a bug as well). Keeping the original write_urb, buffer and flag for now as there are other drivers depending on them. Signed-off-by: Johan Hovold Signed-off-by: Greg Kroah-Hartman --- drivers/usb/serial/usb-serial.c | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) (limited to 'drivers/usb/serial/usb-serial.c') diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c index 8249fd8381fb..941c2d409f85 100644 --- a/drivers/usb/serial/usb-serial.c +++ b/drivers/usb/serial/usb-serial.c @@ -548,8 +548,12 @@ static void usb_serial_port_work(struct work_struct *work) static void kill_traffic(struct usb_serial_port *port) { + int i; + usb_kill_urb(port->read_urb); usb_kill_urb(port->write_urb); + for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i) + usb_kill_urb(port->write_urbs[i]); /* * This is tricky. * Some drivers submit the read_urb in the @@ -568,6 +572,7 @@ static void kill_traffic(struct usb_serial_port *port) static void port_release(struct device *dev) { struct usb_serial_port *port = to_usb_serial_port(dev); + int i; dbg ("%s - %s", __func__, dev_name(dev)); @@ -582,6 +587,10 @@ static void port_release(struct device *dev) usb_free_urb(port->write_urb); usb_free_urb(port->interrupt_in_urb); usb_free_urb(port->interrupt_out_urb); + for (i = 0; i < ARRAY_SIZE(port->write_urbs); ++i) { + usb_free_urb(port->write_urbs[i]); + kfree(port->bulk_out_buffers[i]); + } kfifo_free(&port->write_fifo); kfree(port->bulk_in_buffer); kfree(port->bulk_out_buffer); @@ -920,6 +929,8 @@ int usb_serial_probe(struct usb_interface *interface, } for (i = 0; i < num_bulk_out; ++i) { + int j; + endpoint = bulk_out_endpoint[i]; port = serial->port[i]; port->write_urb = usb_alloc_urb(0, GFP_KERNEL); @@ -945,6 +956,28 @@ int usb_serial_probe(struct usb_interface *interface, endpoint->bEndpointAddress), port->bulk_out_buffer, buffer_size, serial->type->write_bulk_callback, port); + for (j = 0; j < ARRAY_SIZE(port->write_urbs); ++j) { + set_bit(j, &port->write_urbs_free); + port->write_urbs[j] = usb_alloc_urb(0, GFP_KERNEL); + if (!port->write_urbs[j]) { + dev_err(&interface->dev, + "No free urbs available\n"); + goto probe_error; + } + port->bulk_out_buffers[j] = kmalloc(buffer_size, + GFP_KERNEL); + if (!port->bulk_out_buffers[j]) { + dev_err(&interface->dev, + "Couldn't allocate bulk_out_buffer\n"); + goto probe_error; + } + usb_fill_bulk_urb(port->write_urbs[j], dev, + usb_sndbulkpipe(dev, + endpoint->bEndpointAddress), + port->bulk_out_buffers[j], buffer_size, + serial->type->write_bulk_callback, + port); + } } if (serial->type->read_int_callback) { -- cgit v1.2.3